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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.16: Poster
Wednesday, March 28, 2007, 14:00–17:45, Poster A
Kondo effect in low-carrier systems — •Robert Hager and Ralf Bulla — Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Institut für Physik, Universität Augsburg
Recent experiments on dilute U impurities in semiconducting CaB6 show typical Kondo phenomena with a Kondo temperature TK≈ 2K (G.A. Wigger et al., Europhys. Lett. 68, 685 (2004)). This observation is rather unusual for magnetic moments due to 5f electrons because of the large hybridization between impurities and the conduction electrons. We perform numerical renormalization group calculations for an Anderson impurity model with a low concentration of conduction electrons, believed to be the relevant model for (U,Ca)B6. We present results for thermodynamic and dynamic quantities for various carrier concentrations and investigate the crossover from mixed-valent to Kondo behaviour upon decreasing the filling of the conduction band.